Someone else's action should not determine your response.

What we do and think in our own lives, then, becomes of extreme importance as it effects everything we're connected to.

Look at children. Of course they may quarrel, but generally speaking they do not harbor ill feelings as much or as long as adults do. Most adults have the advantage of education over children, but what is the use of an education if they show a big smile while hiding negative feelings deep inside? Children don’t usually act in such a manner. If they feel angry with someone, they express it, and then it is finished. They can still play with that person the following day.